In Federal Parliament, 38 per cent of Senators are women - compared to just 25 per cent of MPs.

''This may be due to people regarding Upper House seats in the Senate as less desirable than seats in the House of Representatives, particularly ambitious people who aim their careers towards working in the House of Representatives where government is formed,'' the ABS says.

The observation raised eyebrows yesterday, with Labor Senator Penny Wong - who is the Minister for Finance and Deregulation - declaring she was ''very proud'' to be a Senator.

''The focus should be on increasing the number of women in the Federal Parliament, not about making one chamber an indicator of a woman's ambition,'' she told News Limited.

''The Senate does important work in examining the detail of legislation and policy.''

Greens Senator Sarah Hanson-Young said she had always wanted to enter the Senate, to hold governments to account.

''I'm very proud to be a young woman in the Senate,'' she said.

''It comes with all the tough decisions about how to juggle work life and family, but I wouldn't give it up for anything.''

The ABS report says some women ''are seen to have a lack of confidence in their abilities and are less likely to put their hands up for promotion''.

''Whereas men are willing to put their hand up for a role where they may not tick some or all of the boxes, some women may only apply for the job if they feel confident they are a good fit for the job,'' it says.

The Federal Government's Workplace Gender Equality Agency Director, Helen Conway, yesterday said it was not true that men are more ambitious.

''Often it's said that women aren't as ambitious as men but that's just not right,'' she told News Limited.

''The overwhelming reason we don't have more women in leadership is the underlying cultural and structural barriers in organisations.

''Flexible work options and careers should be available to men and women so they can balance work and family life.

''This is a family issue, not a woman's problem.''

The ABS report shows that working mothers still spend twice the time as working dads in looking after the kids when they get home.

A woman in full-time work spends an average of six hours and 39 minutes each day taking care of kids - compared to three hours and 43 minutes a day for a man.

Sex Discrimination Commissioner Elizabeth Broderick yesterday said women still do the ''vast majority'' of caring for children, the disabled and the elderly.

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